Where is the Prepar3D.cfg file, and how do I reset it?

Prepar3D stores Prepar3D.cfg in the signed-in Windows user’s roaming AppData folder, under a Lockheed Martin subfolder named for the installed simulator version. Close Prepar3D, rename the file to Prepar3D.cfg.old, and restart the simulator; it will generate a clean replacement while retaining your original settings as a backup.

Where exactly is the Prepar3D.cfg file?

The default Prepar3D configuration file location is %APPDATA%\Lockheed Martin\[Prepar3D version folder]\Prepar3D.cfg. Press Windows key + R, enter %APPDATA%\Lockheed Martin, and open the folder matching the version you use.

For example, the v5 path is %APPDATA%\Lockheed Martin\Prepar3D v5\Prepar3D.cfg. This is not the Prepar3D installation directory under Program Files, a mistake we see frequently.

If Windows displays the file simply as Prepar3D, enable file-name extensions in File Explorer’s View controls. If several Prepar3D versions are installed, each has a separate configuration folder.

How do I reset Prepar3D.cfg safely?

The safest reset is to rename the existing file rather than delete it, leaving an immediate route back to the previous settings.

1. Close Prepar3D completely. Wait until the simulator process has finished before changing its files.
2. Open the correct version folder. Use Windows key + R, enter %APPDATA%\Lockheed Martin, and select the folder matching the Prepar3D version you launch.
3. Back up the configuration. Copy Prepar3D.cfg somewhere safe, then rename the file in its original folder to Prepar3D.cfg.old.
4. Start Prepar3D. With no file named Prepar3D.cfg present, the simulator generates a fresh one using default settings.
5. Test before restoring settings. Reproduce the original problem with the clean configuration before changing graphics, display or add-on options.
6. Reapply settings gradually. Change one group of options at a time so a troublesome setting can be identified rather than copied back unnoticed.

If low frame rates are the only issue, use our Prepar3D performance-tuning checks before repeatedly rebuilding the file. A clean configuration is a diagnostic baseline, not an automatic optimisation.

What does resetting Prepar3D.cfg change?

A reset returns the simulator preferences stored in Prepar3D.cfg to their defaults, including display, graphics and other configuration values held there. It also removes hand-edited tweaks and any add-on-specific entries written into that file.

Resetting the file does not uninstall aircraft, scenery or other add-on files. Prepar3D also stores some settings and registrations in separate files, so a cfg reset is narrower than deleting the complete version folder. An add-on that depends on a custom cfg entry may need its configuration utility run again.

Can I restore my old Prepar3D configuration?

Yes—close Prepar3D, rename the newly generated file, and change Prepar3D.cfg.old back to Prepar3D.cfg. This restores the previous settings but may also restore the fault that prompted the reset.

When diagnosing corruption, we recommend keeping the clean file and manually recreating only the settings you need. Avoid copying an entire cfg between major Prepar3D versions because available options and generated values can differ.

What if Prepar3D does not create a new cfg file?

If no replacement appears, confirm that you opened the folder for the version and Windows account actually running Prepar3D. A version launched for the first time under another Windows account uses that account’s AppData folder.

• Launch Prepar3D once, then exit it cleanly and check the folder again.
• Verify that the old file was genuinely renamed and is not still called Prepar3D.cfg with a hidden extra extension.
• Check that the Windows account can write to the relevant AppData folder.
• Do not create or move the user cfg into the main Prepar3D installation directory.

If a clean cfg does not correct the symptom, another generated file, an add-on or the installation itself may be responsible. Follow the targeted black-screen recovery procedure for a blank display, or use our broader Prepar3D crash-diagnosis steps when the simulator fails during startup or scenario loading.